I have the good fortune to have both of these redrives in my garage as I have gathered parts for my BD-4 project.  I took advantage of timely offers and can only use one of them.  My motor is a 20b built by Bob Darrah.  I like the idea of keeping the RPM's down with the Marcotte drive to 6500, but the RWS drive would allow me to develop additional power at 7500.  I have an IVO prop that I will be using with inflight "controllable" pitch. 

So I throw it out there to you.  Which PRSU do I keep?